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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 379 records · Page 21

Elucidation of complexity and prediction of interactions in microbial communities

Summary Microorganisms engage in complex interactions with other members of the microbial community, higher organisms as well as their environment. However, determining the exact nature of these interactions can be challenging due to the large number of members in these communities and the manifold of interactions they can engage in. Various omic data, such as 16S rRNA gene sequencing, shotgun metagenomics, metatranscriptomics, metaproteomics and metabolomics, have been deployed to unravel the community structure, interactions and resulting community dynamics in situ . Interpretation of these multi‐omic data often requires advanced computational methods. Modelling approaches are powerful tools to integrate, contextualize and interpret experimental data, thus shedding light on the underlying processes shaping the microbiome. Here, we review current methods and approaches, both experimental and computational, to elucidate interactions in microbial communities and to predict their responses to perturbations.

59 BASIC BIOLOGICAL SCIENCES↗

Estimating parameters from rotating ring disc electrode measurements

Rotating ring disc electrode (RRDE) experiments are a classic tool for investigating kinetics of electrochemical reactions. Several standardized methods exist for extracting transport parameters and reaction rate constants using RRDE measurements. Here in this work, we compare some approximate solutions to the convective diffusion used popularly in the literature to a rigorous numerical solution of the Nernst-Planck equations coupled to the three dimensional flow problem. In light of these computational advancements, we explore design aspects of the RRDE that will help improve sensitivity of our parameter estimation procedure to experimental data. We use the oxygen reduction in acidic media involving three charge transfer reactions and a chemical reaction as an example, and identify ways to isolate reaction currents for the individual processes in order to accurately estimate the exchange current densities.

30 DIRECT ENERGY CONVERSION↗

From Edge to HPC: Investigating Cross-Facility Data Streaming Architectures

In this paper, we investigate three cross-facility data streaming architectures, Direct Streaming (DTS), Proxied Streaming (PRS), and Managed Service Streaming (MSS). We examine their architectural variations in data flow paths and deployment feasibility, and detail their implementation using the Data Streaming to HPC (DS2HPC) architectural framework and the SciStream memory-to-memory streaming toolkit on the production-grade Advanced Computing Ecosystem (ACE) infrastructure at Oak Ridge Leadership Computing Facility (OLCF). We present a workflow-specific evaluation of these architectures using three synthetic workloads derived from the streaming characteristics of scientific workflows. Through simulated experiments, we measure streaming throughput, round-trip time, and overhead under work sharing, work sharing with feedback, and broadcast and gather messaging patterns commonly found in AI-HPC communication motifs. Our study shows that DTS offers a minimal-hop path, resulting in higher throughput and lower latency, whereas MSS provides greater deployment feasibility and scalability across multiple users but incurs significant overhead. PRS lies in between, offering a scalable architecture whose performance matches DTS in most cases.

George, Anjus [ORNL] (ORCID:0000000179737061)↗

ParaEMT (NLR's (formerly known as NREL's) EMT Simulator: An Open Source, and HPC-Compatible Large-Scale Power System Electro-Magnetic Transient (EMT) Simulator) [SWR-22-16]

This open-source tool aims to provide a powerful and flexible platform for simulating electromagnetic transients (EMT) of large-scale inverter-based resource (IBR)-dominated power systems. The purpose of making it open source is to foster a community of EMT simulation and assist in exploring new EMT algorithms and applying advanced computational techniques to EMT simulation.

Tan, Jin↗

Targeted Energy Management System Toolset

TEMST integrates advanced sensor systems with advanced computational intelligence, e.g. neural networks and fuzzy arithmetic, to enable effective energy management while minimizing negative human comfort consequences and promoting improved occupant satisfaction. Preliminary work suggests that energy cost reductions above ten percent are easily achievable. In addition to optimizing existing Energy Management Systems (EMS), the proposed toolset will be both resilient and secure in order to proactively maintain a safe level of operational normalcy in response to anomalies and malicious actions.

Rieger, CraigG.↗

Simulation of Multipacting with Space Charge Effect

Here, the electron multiplication on surfaces exposed to an oscillating electromagnetic field causes the phenomenon of multipacting, which can degrade significantly the performance of vacuum RF devices, especially accelerating cavities. It is a serious obstacle to be avoided for normal operation of particle accelerator and their RF components. Many types of room temperature and superconducting accelerating cavities are designed and produced at Fermilab for different projects. The extensive simulations of multipacting in the cavities with updated material properties and comparison of the simulation results with experimental data are routinely performed during electromagnetic design of the cavities. The new advanced computing capabilities made it possible to take the space charge effect into account in the multipacting simulations. The basic new features of multipacting process that appear due to the space charge effect are shown for the classic case of the parallel plates and discussed. As the first practical application of the multipacting simulations with space charge effect the study of multipacting in the low-beta and high-beta 650 MHz elliptical superconducting cavities is also presented.

43 PARTICLE ACCELERATORS↗

Combining de novo and reference-guided assembly with scaffold_builder

Genome sequencing has become routine, however genome assembly still remains a challenge despite the computational advances in the last decade. In particular, the abundance of repeat elements in genomes makes it difficult to assemble them into a single complete sequence. Identical repeats shorter than the average read length can generally be assembled without issue. However, longer repeats such as ribosomal RNA operons cannot be accurately assembled using existing tools. The application Scaffold_builder was designed to generate scaffolds – super contigs of sequences joined by N-bases – based on the similarity to a closely related reference sequence. This is independent of mate-pair information and can be used complementarily for genome assembly, e.g. when matepairs are not available or have already been exploited. Scaffold_builder was evaluated using simulated pyrosequencing reads of the bacterial genomes Escherichia coli 042, Lactobacillus salivarius UCC118 and Salmonella enterica subsp. enterica serovar Typhi str. P-stx-12. Moreover, we sequenced two genomes from Salmonella enterica serovar Typhimurium LT2 G455 and Salmonella enterica serovar Typhimurium SDT1291 and show that Scaffold_builder decreases the number of contig sequences by 53% while more than doubling their average length. Scaffold_builder is written in Python and is available at http://edwards.sdsu.edu/scaffold_builder. A web-based implementation is additionally provided to allow users to submit a reference genome and a set of contigs to be scaffolded.

Salmonella enterica serovar typhimurium↗

Coupling TRACE with nodal neutronics code Ants using the Exterior Communications Interface and VTT's multi-physics driver Cerberus

In this paper a recently developed coupling between system code TRACE and nodal neutronics code Ants is presented. The TRAC/RELAP Advanced Computational Engine (TRACE) is a reactor system code developed by U.S. Nuclear Regulatory Commission (NRC). The code has been designed to analyse loss-of-coolant accidents (LOCAs), operational transients and other accident scenarios in light water reactors. Ants is the reduced order nodal neutronics code of the Kraken framework. The diffusion solution method in Ants is based on the Analytic Function Expansion Nodal method (AFEN) and Flux Expansion Nodal Method (FENM). Rectangular, hexagonal and triangular geometries are supported. Both steady state and burnup problems including micro-depletion can be simulated. The coupling is implemented using VTT's multi-physics driver Cerberus and the Exterior Communications Interface (ECI) which is supplied with TRACE and enables the coupling of TRACE without source code modifications. The main focus in the paper is on describing the TRACE-Ants coupling in detail in order to share to other code developers what we have learned from the ECI based coupling process. The coupled code system is briefly tested by simulating a simple transient in a SMR core initiated by control rod movement. The results of the test calculation look reasonable and more complicated test cases will be modelled in the near future.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Advancing 3D surface imaging: single-axis structured light illumination plenoptic camera with machine learning integration

Structured light illumination (SLI) is a configurable 3D surface imaging modality that can function largely independently of surface texture. At the same time, machine learning (ML) approaches are providing new ways to capture relevant information from SLI patterns, avoiding the need to develop advanced computer vision algorithms. By projecting an optical pattern onto a surface and measuring the apparent distortion of that pattern, one can determine surface topography from a single image. Common realizations of SLI 3D imaging use off-axis SLI to allow for parallax-based determination of depth; however, in constrained geometries, the ability to make single-axis measurements can be of major benefit. While plenoptic imaging (PI) cameras have long been developed for the purpose of single-axis 3D imaging, they are generally reliant on the surface texture of the measured object, thus making them unreliable in certain experimental conditions. Therefore, we present a single-axis 3D SLI plenoptic camera, which combines the single-axis benefits of PI technology while using coaxial SLI to maintain indifference to surface conditions. We also present a study of the camera capabilities paired with the development of several algorithms, including traditional feature tracking methods as well as ML methods, which are found to enhance resolution and range. We report depth sensitivity down to 0.2% $\frac{dz}{z_0}$. The single-axis SLI 3D plenoptic camera demonstrates potential applicability for in-situ topographical measurements under a wide range of conditions including, but not limited to, objects without trackable surface texture, high temperatures, and constrained geometry environments.

Imaging systems↗

Virtual Observation System for Earth System Model: An Application to ACME Land Model Simulations

Investigating and evaluating physical-chemical-biological processes within an Earth system model (EMS) can be very challenging due to the complexity of both model design and software implementation. A virtual observation system (VOS) is presented to enable interactive observation of these processes during system simulation. Based on advance computing technologies, such as compiler-based software analysis, automatic code instrumentation, and high-performance data transport, the VOS provides run-time observation capability, in-situ data analytics for Earth system model simulation, model behavior adjustment opportunities through simulation steering. A VOS for a terrestrial land model simulation within the Accelerated Climate Modeling for Energy model is also presented to demonstrate the implementation details and system innovations.

58 GEOSCIENCES↗

Variable Grid Method

NETL’s Variable Grid Method (VGM) is a novel approach that leverages GIS capabilities to simultaneously visualize and quantify spatial data trends and underlying data uncertainty. The flexible VGM approach utilizes a range of spatial datasets and uncertainty quantifications, which can be calculated using data related to sample density, sample variance, interpolation error, multiple simulations, etc., to create an integrated visualization of data and uncertainty. The intuitive manner of the VGM helps communicate the relationship between uncertainty and spatial data to effectively guide research, support advanced computation analyses, and helps inform research, management and policy decisions. The VGM approach is being developed into a standalone tool designed to integrate into a variety of research workflows, providing users the capabilities to utilize the VGM for their datasets, analysis, and models in support of their decision making needs. The VGM approach was developed as part of NETL’s Offshore portfolio. It was further matured and utilized in projects associated with both NETL’s Unconventional Resources and Carbon Storage portfolios, and is now being further developed by Varigrid, LLC.

Carbon Storage↗

High-performance computing in water resources hydrodynamics

In this work, we present a vision of future water resources hydrodynamics codes that can fully utilize the strengths of modern high-performance computing. The advances to computing power, formerly driven by the improvement of central processing unit processors, now focus on parallel computing and, in particular, the use of graphics processing units (GPUs). However, this shift to a parallel framework requires refactoring the code to make efficient use of the data as well as changing even the nature of the algorithm that solves the system of equations. These concepts along with other features such as the precision for the computations, dry regions management, and input/output data are analyzed in this paper. A 2D multi-GPU flood code applied to a large-scale test case is used to corroborate our statements and ascertain the new challenges for the next-generation parallel water resources codes.

54 ENVIRONMENTAL SCIENCES↗

Knowledge-Based Parallel Performance Technology for Scientific Application Competitiveness Final Report

The primary goal of the University of Oregon's DOE "œcompetitiveness" project was to create performance technology that embodies and supports knowledge of performance data, analysis, and diagnosis in parallel performance problem solving. The target of our development activities was the TAU Performance System and the technology accomplishments reported in this and prior reports have all been incorporated in the TAU open software distribution. In addition, the project has been committed to maintaining strong interactions with the DOE SciDAC Performance Engineering Research Institute (PERI) and Center for Technology for Advanced Scientific Component Software (TASCS). This collaboration has proved valuable for translation of our knowledge-based performance techniques to parallel application development and performance engineering practice. Our outreach has also extended to the DOE Advanced CompuTational Software (ACTS) collection and project. Throughout the project we have participated in the PERI and TASCS meetings, as well as the ACTS annual workshops.

97 MATHEMATICS AND COMPUTING↗

Final Report for "SciDAC Center for Simulation of Wave-Plasma Interactions (CSWPI)"

This project has provided for the participation of the PI (Dr. David Smithe) and other Tech-X Corporation personnel in the larger CSWPI (Center for the Study of Wave Plasma Interactions) SciDAC project. In addition to collaborative efforts in several areas, the PI's thrust research area has focused on the tokamak edge, in the vicinity of the antenna structure, and on the specific physics of interest to the edge, including RF sheath formation. This interest is being driven by a desire to understand measured anomalous power losses that are associated with the edge region. Realistic true 3D geometry simulation capability of the operating antenna, immersed in the edge plasma, has been developed. Geometry accuracy is at the same degree as CAD drawings themselves. In addition, the plasma model includes an RF sheath potential calculation for cells where the plasma is in contact with the metallic structure of the antenna. This capability, in a time-domain simulation, is presently unique. This model can be used to immediately estimate local sheaths (and possibly sputtering damage caused by them), and will be used in the future to model long-range sheaths. Modeling on this scale, in 3D, clearly requires very large scale parallel processing and advanced computing. Ultimately, the desire is to provide quantitative prediction of parasitic edge loss, and edge plasma behavior, analogous to the quantitative core models that have long been a staple of the RF modeling regime.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

3D COMSOL Simulations for Thermal Deflection of HFIR Fuel Plate in the "Cheverton-Kelley" Experiments

Three dimensional simulation capabilities are currently being developed at Oak Ridge National Laboratory using COMSOL Multiphysics, a finite element modeling software, to investigate thermal expansion of High Flux Isotope Reactor (HFIR) s low enriched uranium fuel plates. To validate simulations, 3D models have also been developed for the experimental setup used by Cheverton and Kelley in 1968 to investigate the buckling and thermal deflections of HFIR s highly enriched uranium fuel plates. Results for several simulations are presented in this report, and comparisons with the experimental data are provided when data are available. A close agreement between the simulation results and experimental findings demonstrates that the COMSOL simulations are able to capture the thermal expansion physics accurately and that COMSOL could be deployed as a predictive tool for more advanced computations at realistic HFIR conditions to study temperature-induced fuel plate deflection behavior.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

Summary Report on Liquid-Liquid Contactor Scoping Experiments and Validation Test Case Definition

This report presents an overview of a set of wide ranging experiments that was conducted during the first half of FY12 using the capability of the Contactor Electrical Resistance Tomography (CERT) Facility. This facility includes the capability for multiphase measurements of flow in liquid–liquid contactors using ERT as well as high-speed imaging with the current test focus on an instrumented engineering-scale annular centrifugal contactor having a 5 inch rotor (CINC-V5). The purpose of the efforts during this current FY are to explore a range of flow conditions for multiphase operation to gain broad insight into observable trends and quantities after which detailed measurements will be made for specific controlled test conditions to provide data for validation of advanced computational fluid dynamics models which are being developed under a separate work package (FT-12AN030901). In addition to the Redlake X5plus camera, a Redlake MotionPro Y7 camera was also available on loan from another research group at Argonne. The Y7 is capable of grayscale imaging at 7500 frames per second at full resolution (1920×1080) and has excellent light sensitivity (can be used for time-resolved particle image velocimetry (PIV)). This camera was used for the bubble imaging described in Section 2.3. Imaging at the bubble scale was done using a Infinity K1 CentriMax lens with an MX-4 objective attachment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

FY12 Summary Report on Liquid-Liquid Contactor Experiments for CFD Model Validation

This report presents a summary of preliminary experiments performed in the latter half of FY12 using the capability of the Contactor Electrical Resistance Tomography (CERT) Facility. This facility includes the capability for multiphase measurements of flow in liquid–liquid contactors using ERT as well as high-speed imaging with the current test focus on an instrumented engineering-scale annular centrifugal contactor having a 5 inch rotor (CINC-V5). In addition, a smaller CINC-V2 (2 inch rotor) contactor was also added to the facility and made possible the exploration of equipment scaling for liquid–liquid operation. The purpose of the efforts during this current FY were to explore a range of flow conditions for multiphase operation to gain broad insight into observable trends and quantities after which detailed measurements will be made for specific controlled test conditions to provide data for validation of advanced computational fluid dynamics models which are being developed under a separate work package (FT-12AN030901). In FY13, this project and the CFD modeling project are to be combined into a single Work Package named “Contactor Modeling and Validation Data”.

42 ENGINEERING↗

Optimization Studies for ISOL Type High-Powered Targets

The research studied one-step and two-step Isotope Separation on Line (ISOL) targets for future radioactive beam facilities with high driver-beam power through advanced computer simulations. As a target material uranium carbide in the form of foils was used because of increasing demand for actinide targets in rare-isotope beam facilities and because such material was under development in ISAC at TRIUMF when this project started. Simulations of effusion were performed for one-step and two step targets and the effects of target dimensions and foil matrix were studied. Diffusion simulations were limited by availability of diffusion parameters for UC x material at reduced density; however, the viability of the combined diffusion?effusion simulation methodology was demonstrated and could be used to extract physical parameters such as diffusion coefficients and effusion delay times from experimental isotope release curves. Dissipation of the heat from the isotope-producing targets is the limiting factor for high-power beam operation both for the direct and two-step targets. Detailed target models were used to simulate proton beam interactions with the targets to obtain the fission rates and power deposition distributions, which were then applied in the heat transfer calculations to study the performance of the targets. Results indicate that a direct target, with specification matching ISAC TRIUMF target, could operate in 500-MeV proton beam at beam powers up to ~40 kW, producing ~8 10 13 fission/s with maximum temperature in UCx below 2200 C. Targets with larger radius allow higher beam powers and fission rates. For the target radius in the range 9-mm to 30-mm the achievable fission rate increases almost linearly with target radius, however, the effusion delay time also increases linearly with target radius.

43 PARTICLE ACCELERATORS↗